Benzidine yellow type pigment

ABSTRACT

IS PRODUCED BY TETRAZOTIZING 3,3&#39;&#39;,5,5&#39;&#39;-TETRACHLOROBENZIDINE AND THEN COUPLING THE TETRAZOTIZED PRODUCT WITH ACETO-ACET-OPHENETIDIDE. In a preferred method N,N&#39;&#39;-diacetyl-3,3&#39;&#39;,5,5&#39;&#39;tetrachlorobenzidine is hydrolyzed to the corresponding amine in situ in the acid solution which is to be used for the tetrazotizing step.   A benzidine yellow type pigment of unusually good lightfastness and superior strength is described. The pigment, which is a compound of the formula

[ 1 March 6, 1973 [54] BENZIDINE YELLOW TYPE PIGMENT [75] Inventor: Joseph W. Conley, Fort Edward,

[73] Assignee: Hercules Incorporated, Wilmington,

Del.

[22] Filed: March 12, 1969 [21] App1.No.: 806,724

52 us. c1 ..260/176, 106/23, 106/288 Q, 260/141 51 Im. Cl.....C09b 35/10, C09b 35/24, C09d 11/16 58 Field 61 Search ..260/176 [5 6] References Cited UNITED STATES PATENTS 1,962,511 7/1934 Krzikalla et a1. ..260/181 3,403,200 9/1968 Randall ..260/178 3,025,287 3/1962 Ribka ..260/176 3,161,633 12/1964 Lenoir et 31.. ..260/176 3,030,354 4/1962 Ribka ..260/176 OTHER PUBLICATIONS Hduben-Weyl, Methoden der Organischen Chemie, v61. 11/1, 1957, pp. 925-931.

Primary Examiner-Floyd D. I-Iigel Attorney-Charles L. Board [57] ABSTRACT A benzidine yellow type pigment of unusually good lightfastness and superior strength is described. The pigment, which is a compound of the formula is produced by tetrazotizing 3 ,3 ,5 ,5 tetrachlorobenzidine and then coupling the I 1 Claim, No Drawings BENZIDINE YELLOW TYPE PIGMENT The present invention relates to a novel water-insoluble disazo dyestuff of the benzidine yellow class which is particularly useful as a pigment and to a process for 5 preparing thesame. More particularly, it relates to the compound of the formula 3 Thus, it is the principal object of this invention to provide from available intermediates a new disazo pigment of the benzidine yellow class having the desirable characteristics of masstone transparency and greenish yellow hue, but having excellent lightfastness and high tinctorial strength.

In accordance with this invention it has now been found that the above object is accomplished by using 3,3,5,5'2,2,5,5'-

tetrachlorobenzidine of Ribka andcoupling it with 40 aceto-acet-o-phenetidide.

The new pigment of this invention is a yellow, water insoluble dyestuff and can be prepared by tetrazotization of one mole of 3,3',5,5'-tetrachlorobenzidine followed by coupling with 2 moles of aceto-acet-ophenetidide, preferably under slightly acid conditions. It can also be prepared from the somewhat cheaper diacetyl derivative of 3,3',5,5'-tetrachlorobenzidine by hydrolyzing the derivative to the amine in situ in the acid solution which is subsequently to be used for the tetrazotization step, tetrazotizing and then coupling as above. H 7

The following examples illustrate the preparation of the pigment of the invention using both techniques.

Unless otherwise indicated all parts referred to are.

parts by weight.

EXAMPLE 1 6 recovered as a yellow powder.

with stirring for 2 hours to effect clear solution, after which time the solution was downed into 400 parts of crushed ice to lower the temperature to 0-5 C. and a small quantity of sulfamic acid added to remove excess nitrite.

In a separate vessel a solution prepared by dissolving 22.75 parts of aceto-acet-o-phenetidide in 900 parts of water containing 4.5 parts of sodium hydroxide at 35-40 C. was added to 140 parts of anhydrous sodium acetate and the resulting solution diluted with water to 3,000 parts at 20C. The resulting suspension was then adjusted to a pH of 6.0-6.1 with 700 percent acetic acid approximately 9.8 parts being required.

The coupling was effected by adding the above tetrazotized solution over a 30 minute period to the phenetidide suspension with agitation while maintaining the temperature at 20C., after which time the pH of the resulting color slurry was adjusted to 4.04.1

. with 5 percent sodium hydroxide solution. When the reaction was complete (as indicated by a negative test 0 with 1-a.rnino-8-naphthol-3,fi-disulfonic acid), the

color slurry was heated to 97 C. at the rate of 1C. per minute, held for 15 minutes at this temperature and then drowned to 60C. and filtered. The pigment filter cake was then washed thoroughly with water and dried at 60C. The pigment was recovered in the form of a yellow powder.

EXAMPLE 2 This example illustrates the preparation of the pigment of this invention starting with the diacetyl derivative of 3,3',5,5-tetrachlorobenzidine. To a vessel containing 105.5 parts of 93.2 percent sulfuric acid was added 20.3 parts of N,N'-diacetyl 3,3',5,5'- tetrachlorobenzidine and the vessel contents heated to 130C. to effect a clear solution. The solution was then cooled to 60-70C. and added to a nitrosyl sulfuric acid solution prepared by adding, with agitation, 7.8 parts sodium nitrite percent) slowly and carefully to prevent gassing to 105.5 parts of 93.2 percent sulfuric acid. The resulting solution was maintained at 50C. for 45 minutes after which time it was drowned into 400 parts of crushed ice to lower the temperature to 05C. and a small quantity of sulfarnic acid added to remove excess nitrite.

Coupling of the above tetrazo-solution with 22.75

' parts of aceto-acet-o-phenetidide and isolation of the pigment was carried out in accordance with the procedure of Example 1. The resulting pigment was EXAMPLE 3 The pigment of Example 1 was evaluated for strength and lightfastness on paper drawouts and compared with two known pigments of similar chemical structure, namely, the commercially available pigment (CI. 21105) made from 3,3'-dichlorobenzidine coupled with aceto-acet-o-anisidide (designated as pigment A) and with a pigment prepared according to the procedure of Example 1 above except that 2,2,5,5- tetrachlorobenzidine, instead of 3 ,3 ,5 ,5 tetrachlorobenzidine was coupled with aceto-acet-ophenetidide (designated as pigment B).

The inks used for these drawouts were prepared by thoroughly mixing 0.3 part of pigment with 1.0 part of lithovarnish and grinding to a smooth masstone ink on a Hoover Muller using 4 cycles with 100 revolutions per cycle, and then reducing the masstone ink with either zinc white paste or aluminum hydrate paste. For strength and hue evaluations, 1 part of the masstone ink was reduced with 50 parts of zinc white paste and the paper drawouts compared visually. For the lightfastness evaluations, parts of the masstone ink were reduced with parts of aluminum hydrate paste and the paper drawouts exposed in a Fadeometer for 450 hours.

The pigment of Example 1 was slightly superior in lightfastness to pigment B and was far superior to pigment A, and was about 3 timesstronger than pigment B and slightly less strong than pigment A. The masstone ink of the pigment of this invention was highly transparent, being more transparent than the ink of pigment B and much more transparent than the ink of pigment A. All three pigments had hues of approximately the same order and were relatively greenish yellows.

What I claim and desire to protect by Letters Patent is:

1. The compound having the formula UNITED STATES PATENT OFFICE (5369) CERTIFECATE GF CORRECTEON Patent No. 3,119,658 Dated. M 6 1973 Inventofls) Joseph W. Conlev (Case 2) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 39 of printed patent;

"3,3 ,5,5 2,2 ,5,5"" should read 3,3'5-,5'-tetrachlorobenzidineinstead of the Column 2,. line 21 of printed patent;

"700" should read --70'- Signed and sealed this 10th day of July 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. ene Tegtmeyer v Actmng Commissioner of Patents Attesting Officer 

